Roving cutter

ABSTRACT

A lightweight, compact roving cutter for chopping fiberglass roving into short fiber segments, and used in conjunction with a hand-held resin spray gun, has a cutter roller carrying a plurality of blades, a back-up roller cooperating with the cutter roller and the blades thereof for breaking or cutting the roving, and an idler roller cooperating with the back-up roller for feeding roving between the cutter and the back-up roller. The back-up roller is mounted for movement toward and away from both the cutter and the idler rollers in substantially equal increments relative to each, and a positive displacement adjusting means is connected with the back-up roller for controlling the clearance between the back-up roller and both the cutter and the idler rollers, the adjusting means including a manually operable portion remote from said cutter, whereby an operator may conveniently and accurately adjust the clearances between the rollers while the cutter is operating.

This is a division of application Ser. No. 586,206, filed June 12, 1975,U.S. Pat. No. 4,001,935.

BACKGROUND OF THE INVENTION

Fiberglass reinforced plastics have been widely accepted by industry. Aparticularly convenient mode of forming such reinforced plastics residesin the simultaneous spray application of liquid resin and cut or choppedfiberglass roving. Pursuant to this technique, a fiberglass cutter orchopper is mounted on a spray gun and fed with a continuous strand ofroving which the chopper breaks into small pieces of predeterminedlength and discharges into the liquid spray from the spray gun, wherebythe cut or chopped fibers are wetted and sprayed simultaneously with theresin into a mold or other forming vehicle.

One type of prior art device for cutting or breaking fiberglass rovinginto short fibers is shown in U.S. Pat. No. 3,011,257 to Bamberger.Combined resin spray guns and choppers are shown by way of example inthe U.S. Pat. Nos. to Anderson 2,933,125, Nawalanic 2,995,173 andScheinert 3,212,717. The structures shown in these patents are ratherlarge, heavy and cumbersome. More compact arrangements of a spray gunand a detachable cutter assembly are shown in the U.S. Pat. Nos. toJones 3,155,320 and Fram 3,491,443. However, even the latterarrangements are quite heavy and cumbersome.

In general, fiberglass choppers comprise a cutter rotor or rollercarrying a plurality of blades and a back-up roller between which theroving is fed, the blades bearing on the back-up roller and chopping orbreaking the roving as it passes between the two rollers. To facilitatethe cutting action, the back-up roller is usually comprised of aresilient surface material. If the contact between the two rollers istoo severe the back-up roller or the blades, or both, wear quickly andhave to be replaced; on the other hand, if there is insufficientcontact, cutting is incomplete or does not occur. To solve this problem,the Jones U.S. Pat. No. 3,155,320 provide a simple adjustment for theback-up roller but had the disadvantages of necessitating stopping thecutter to make the adjustment and requiring both hands of the operatorto do so. The Fram U.S. Pat. No. 3,491,443 provided a complicated,self-adjusting feature for the rollers, but had a non-driven cutterroller structure which was used with a driven back up roller. Further,the adjustment of Fram's roller was difficult and required that thecutter be stopped since the adjustment was not easily accessible to theoperator. In addition, Fram utilized a third roller engaging the back uproller to aid in feeding the roving to the blades, but no adjustment wasprovided to vary the contact with the feed roller as the back up rollerwore down.

The blades of the cutter roller or rotor wear and need to be replaced,and such should be done easily and quickly. However, replacement couldnot be quickly accomplished in prior art cutters. For example, in thestructure of Jones U.S. Pat. No. 3,155,320 a total of eight separatefasterners had to be removed and replaced in order to change the blades.Further, the cutter rotor was usually held in place on the chopper andcould not be removed as a unit so that blade replacement was quitedifficult and time consuming.

Cutting the roving into short segments is just one function of thecutter; it must also distribute the cut fibers in a pattern compatiblewith that of the spray gun so that the cut fibers are completely, ornearly completely, wetted by the resin spray. While some prior artattempts have been made to achieve such result, many have avoided orignored the problem. For example, Bamberger U.S. Pat. No. 3,011,257attempted to avoid the problem by using a separate cutter and,presumably, a separate spray gun. Of course Bamberger's approach had thedisadvantage of greatly increased labor costs in that two separateoperations had to be performed. Another approach to the problem wastaken by Fram U.S. Pat. No. 3,491,443, wherein exhaust air from the airmotor and additional air from the air line were used to hold the cutfibers together during discharge, with the pattern of the cut fibersupon discharge depending mainly upon the physical shape of the outletnozzle. Scheinert U.S. Pat. No. 3,212,717 discloses the use of air forconveying cut roving, but not for controlling the discharge patternthereof, somewhat similar to Bamberger.

SUMMARY OF THE INVENTION

The roving cutter of the present invention overcomes and eliminates thedisadvantages of the prior art and is particularly adapted to be used inconjunction with a resin spray gun. The cutter comprises a mountingplate, an integrated air motor, a cutting roller with a plurality ofreadily replaceable blades, a cooperating readily replaceable back-up orfriction roller, an idler or roving feed roller, adjustment means forvarying the clearances between all of the rollers, and means formatching the discharge pattern of the cut roving to the spray pattern ofthe resin spray gun.

The back-up roller is adjustable and provided with positive displacementadjustment means for varying the relative positions between it and boththe cutter roller and the feed roll. Additionally, the adjustment meansaccommodates roller adjustment while the cutter is operating so that adynamic clearance can be set instead of having to stop the cutter andeffect adjustment by a "cut and try" method. The adjustment is such thatthe clearance between the feed roller and back-up roller and theclearance between the back-up roller and cutter roller are kept nearlyequal at all times, and the adjustment is positive and not reliant onsprings or spring pressure.

These and other advantages of the roving cutter of the present inventionwill become apparent from the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a frontal perspective view of a preferred embodiment of theroving cutter of the present invention shown assembled onto a resinspray gun;

FIG. 2 is a perspective view of the roving cutter from the rear, withthe roller cover removed;

FIG. 3 is a generally vertical cross-sectional view of the cutter;

FIG. 4 is a vertical longitudinal section of the cutter, takensubstantially along line 4--4 of FIG. 3, with portions thereof brokenaway;

FIG. 5 is a fragmentary horizontal section, taken substantially alongline 5--5 of FIG. 4;

FIG. 6 is an exploded perspective view of the cutter roller and blades;

FIG. 7 is an enlarged fragmentary cross-sectional view of the cutterroller;

FIG. 8 is an enlarged elevational view of one of the cutter blades;

FIG. 9 is a vertical longitudinal section taken substantially along line9--9 of FIG. 3; and

FIG. 10 is a horizontal section taken substantially along line 10--10 ofFIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, a roving cutter or chopper 20 provided pursuant to thepresent invention is shown assembled onto a hand-held resin spray gun22, such as disclosed in Krohn et al, U.S. patent application Ser. No.366,599, filed June 4, 1973, suitable for spraying plural componentplastic materials such as polyester resins. The two components of theresin are supplied to the spray gun 22 by hoses 24 and 26, and areadapted to be individually sprayed from nozzles 30 and 32, under controlof a manually operated trigger 34. The spray nozzles 30 and 32 aremounted in angularly convergent relationship so that the spraystherefrom commingle and intermix to form a suitable resin mixture. Inaddition, compressed air is supplied to the gun via hose 28, also undercontrol of the trigger 34, for operating the chopper 20.

The chopper or cutter 20 is mounted on top of the spray gun 22 by meansof an L-shaped bracket 36, the horizontal portion of the bracket havinga rear opening and an arcuate forward slot for reception of screws 38adjustably mounting the bracket on the gun, and the vertical portion ofthe bracket having a pair of arcuate slots therein for reception ofscrews 40 adjustably mounting the cutter on the bracket so that thecutter 20 may be pivoted both horizontally and vertically relative tothe spray gun 22 to properly align its outlet with the liquid spraypatterns from the nozzles 30 and 32.

The cutter 20 comprises a mounting plate 42 to which the screws 40 aresecured. On one side, the mounting plate 42 carries and forms part of anair motor 44 which drives the cutter 20.

As shown in FIG. 3, the air motor 44 includes a rotor cavity 46 formedby a surface 48 of the mounting plate 42, a cylindrical opening 50 in acentral body 51, and an end plate 52. A vaned rotor 54 having a shaft 53is rotatably mounted in the cavity 46 eccentrically of the cylindricalopening 50 in the body 51. The shaft 53 of the rotor is journalled onbearings 56 and 58 located in the openings 60 and 62 in the mountingplate 42 and end plate 52, respectively. The rotor 54 has a plurality ofradial slots therein, each of which slidably receives a radiallyextending vane 55. The radially outer edges 64 of the vanes 55 sealagainst the cylindrical peripheral wall of the opening 50, and the sideedges 65 and 67 of the vanes seal against the mounting plate 42 and theend plate 52. Also, the ends of the rotor 54 seal against the surface 48of the mounting plate 42 and the end plate 52.

The end plate 52 and central body 51 are aligned with one another andthe mounting plate 42 by roll pins (not shown) and are secured inassembled relation by a plurality of cap screws 69. The end plate 52 isenclosed by a decorative cover 66 which is held in place by screws 63.The cover 66 cooperates with an O-ring 68 located in a groove in theouter surface of plate 52 to seal the bearing 58 and the one end of thecavity 46. A seal 84 is mounted about the shaft 53 in the opening 60 inthe plate 42 to seal the bearing 56 and the opposite end of the airmotor cavity 46.

Referring to FIGS. 4 and 5, air is supplied to the air motor 44 from asource of pressurized air, via a hose 71 extending between the air motorand an air outlet fitting 70 on the spray gun 22. The outlet fitting 70is, of course, located downstream of the trigger 34, so that air issupplied to the motor of the cutter only when the gun trigger isactuated. The air hose 71 is connected to an inlet passage 72 in thecentral body 51 of the motor 44. A motor speed control passage 73intersects the inlet passage 72, and the flow of air through the latterpassage is regulated by a speed control valve 74 of the needle valvetype located at the upstream end of passage 73; the valve including astem threaded in the body 51 and extending to the exterior thereof andmanually operable to control the amount of air fed to the motor and thusthe speed of the motor. The passage 73 includes a transverse portion 79in the central body 51 and extending into the plates 42 and 52 tocommunicate with horizontal passages 75 in the mounting plate 42 and theend plate 52, the latter passage in turn leading into arcuate air inletports 76 for the motor formed in the inner surfaces of the mountingplate 42 and the end plate 52 adjacent the rotor 54. The outer ends ofthe passage 75 may be closed by set screws or pressfit steel balls, asindicated at 77 in FIG. 5.

Air supplied under pressure to the ports 76 drives the motor in aconventional manner, counterclockwise as viewed in FIG. 4. Most of theair exits from the cavity 46 through a generally radial exhaust port 78in the central body 51, the outer end of which is fitted with a muffler80 to reduce noise. A small portion of the exhaust air is vented fromthe cavity 46 through a bore 82 in the mounting plate 42 for purposeshereinafter described.

As shown in FIG. 3, the shaft 53 of the air motor 44 extends through theopening 60 in the mounting plate 42 to the opposite side thereof, andcarries and directly drives a cutter rotor or roller 86.

As shown in FIGS. 6 and 7, the cutter roller 86 comprises a generallycylindrical body 88 of about 1/4 inches in diameter, having eight slots90 formed in the surface thereof. The slots 90 are not parallel to thelongitudinal axis of the cutter but are inclined or skewed relative tosaid axis to distribute the fiber cutting or breaking action. The endsof the body 88 are recessed and have annular grooves 92 formed thereinin communication with the slots 90. An inner end cap 98 having anaxially extending projection or rim 99 of a diameter equal to but of athickness less than that of the annular groove 92 is secured, as byscrews 101, to the end of the body 88 adjacent the mounting plate 42. Asimilar outer end cap 100 having an identical rim 99 is releasablysecured to the opposite or outer end of the body 88 by a singlefastener, preferably in the form of a threaded screw 102 which engagesin a threaded bore 104 in the body 88. Both the end caps 98 and 100 andthe body 88 have central openings for receiving the shaft 53, and theend cap 98 and the body 88 have a key slot for slidable reception of akey 105 on the shaft 53, whereby the shaft and roller are connected forconjoint rotation. However, pursuant to the present invention, thecutter roller 86 is quickly releasable from the shaft 53 and is heldthereon only by a snap-type connection such as by a ball 106 releasablyengaging in an annular notch 108 in the shaft. The ball 106 is biasedtoward the shaft 53 by a spring 110 located in an opening 112 in thebody 88, the outer end of the opening 112 being closed by a plug 114.The notch 108 is so located on the shaft 53 that the inner end of theroller 86 is spaced a short distance from the mounting plate 42, wherebya screw driver can be inserted between the plate and the roller to popthe roller off the shaft.

Each of the slots 90 in the cutter roller 86 is adapted to carry aspecially shaped cutting blade 116, one of which is shown in FIG. 8.Each blade 116 is a generally elongated, rectangular thin blade, muchlike a razor blade, with one longitudinal edge sharpened as indicated at118. The opposite edge 120 of the blade is somewhat shorter in length,and the two side edges 122 are provided with inwardly extending notches124. Each blade is so dimensioned relative to the slots 90 that thenotches 124 align with the annular recesses 92 in the roller, so thatwhen the blade is installed in the roller the rims 99 of the end caps 98and 100 engage in the notches 124 and retain the blade in the roller 86.The blade is completely symmetrical about a plane midway between itsedges 122 and therefore reversibly mountable in the roller.

By utilizing a roller approximately 11/4 inches in diameter with eightequally spaced slots therein, and providing for mounting in the rollerof any number of blades from one to eight, very convenient adjustment isprovided for the length of the fiber segments into which the roving iscut. That is, with one blade, the roving would be cut into four inchlong segments; with two equally spaced blades into two inch segments;with four equally spaced blades into one inch segments; and with eightblades into one-half inch segments. Generally, one-half inch segmentsand one inch segments are those most regularly desired. Also, mixedlengths could be obtained if desired by using other numbers, and/orspacings of blades, for example, six to obtain some one-half inch longsegments and some one inch long segments. In any event, with the end cap100 removed, the desired number of blades are inserted in the selectedslots 90 in the roller and slid into engagement with the rim 99 of theend cap 98, whereupon the cap 100 may be attached by the screw 102 tolock the blades on the rotor. Then the rotor is simply slid onto theshaft 53 with the key slots aligned with the key 105 until the ball 106snaps into place in the groove 108.

Should it be desired to change the blades 116 on the cutter roller 86, atool such as a screw driver may be inserted in the space between themounting plate 42 and the roller 86 and the latter simply pried off theshaft 53. The single screw 102 is then removed along with the end cap100, and the blades are exchanged. The cap 100 and screw 102 are thenreplaced, and the cutter rotor 86 is snapped back onto the shaft 53. Ofcourse for a faster change, a second roller 86 with new blades thereincould simply be substituted for the first roller.

In order to cut or break the roving as it passes thereover, and also todrive the roving, the cutter roller 86 cooperates with a back-up orfriction roller 126. The roller 126 also cooperates with an idler orfeed roller 127, hereinafter described, to feed the roving through thecutter.

As shown in FIGS. 3 and 9, the back-up roller 126 comprises an interiorhub member 128 on which is mounted a replaceable cylindrical rubber orother resilient sleeve 130 of about the same outside diameter as thecutter roller 86. The hub member 128 contains a pair of ball bearings132 for rotatably mounting the roller on a shaft 134 which is carried bythe mounting plate 42 in a manner to be described. The roller 126 isheld in proper location on the shaft 134 by a shoulder on the shaftadjacent the inner end thereof and by a retainer nut 135 at the outerend thereof, the shoulder and the nut engaging the inner races of thetwo bearings 132.

Means 136 are provided for adjusting the relative position of thefriction roller 126, so as to adjust the clearance between the rollers86 and 126, and thus, the cutting pressure the blades 116 exert on theroving. Preferably, the means 136 comprises a pivotal link 140 (FIG. 9)which at its lower inner end mounts the shaft 134 and which at its otherend is pivotally mounted on the mounting plate 42 by a large flat headscrew 142. The link 140 fits within a recess 143 formed in the mountingplate 42 so as to prevent the link from protruding. The relativeposition of the link 140 may be altered by positive displacementadjustment means in the form of a screw 144, which is interlocked withthe lower inner end of the link and is threaded through the plate 42 foradjustment from the exterior thereof.

The screw 144 has a ball-shaped head 146 on its inner end which fits ina spherical recess or socket 147 formed in the link 140 so that theadjusting screw 144 and link 140 are positively connected together, thesocket including a radial slot for passage of the stem connecting thescrew and the ball head. The upper portion of the screw 144 isthreadedly engaged in a threaded passage 148 formed through the mountingplate 42 and has a knurled lock nut 150 and an adjustment knob 152thereon. Thus, by rotating the screw 144, the link 140, shaft 134 andfriction roller 126 are positively moved in and out relative to thecutter roller 86, as indicated by dotted lines and primed referencenumerals in FIG. 9. By loosening the lock nut 150, the knob 152 may berotated, even and most particularly while the chopper is operating, toadjust the location of the back-up or friction roller 126 to obtain theoptimum adjustment between the rollers 126 and 86 in terms both ofroving feed and cutting or breaking action. Then, the lock nut istightened down on the plate 42 to lock the screw and the roller 126 inthe desired and proper location. The roller thereafter cannot move fromits adjusted location and the cutting or breaking action is positive,and not reliant upon springs or spring pressure. Also, the adjustment isachieved entirely by hand without need for tools.

As will further be appreciated from FIG. 9, unlike prior art devices,movement of the roller 126 by the adjustment means 136 is such thatapproximately the same clearance is maintained between the idler roller127 and friction roller 126, indicated at C₂, as maintained between thefriction roller and cutter roller 86, indicated at C₁, so that the idlerroller is not rendered ineffective by wearing and/or adjustment of thefriction roller. This desirable result is achieved by the use of thepivotal adjustment and by selecting the proper locations for the roller126 and the pivot point of the link 140.

The idler roller 127 is smaller than the other rollers, and comprises atubular member 154 having a pair of bearings 156 which are mounted on ashaft 158. The inner end of the shaft 158 is threaded and secured to themounting plate 42. The outer end of the shaft 158 carries a nut forretaining the roller on the shaft, and also has a threaded extension fora purpose to be described hereinafter.

A roving guide 166 is secured to the mounting plate 42, upwardly andrearwardly from, and has three openings 168 therein which lead toward,the bight between the friction roller 126 and idler roller 127. One ormore strands of roving are lead through the roving guide holes 168 intothe bight between the idler roller 127 and back-up roller 126 and intothe bight between the back-up roller and cutter roller 86. Thus, as thecutter roller 86 is rotated by the air motor 44, the friction roller 126and idler roller 127 are also rotated, pulling the roving into thecutter 20. The blades 116 cut the roving into short segments of fiber,which are then thrown horizontally forward from the cutter and back-uprolls. The idler roller 127 cooperates with the back-up roller 126 toassure continuous feed of roving to the cutter rotor during cutting.

To protect personnel from injury and to confine the roving as it isbeing cut, the rollers 86, 126 and 127 are enclosed by a protectivecover 159 of generally cup-shape. The cover is designed to fitconformably around the rollers and has a slot 160 therein for receptionof the roving guide 166. A hole is formed in the outer wall of the coverin alignment with the idler roller shaft 158, and a thumb nut 164, whichis rotatably trapped in the hole in the cover, is adapted to be threadedonto the shaft extension to detachably secure the cover to the remainderof the cutter. Forwardly of the rollers 126 and 86, the top and bottomwalls of the cover are sloped convergently forward to define a generallyrectangular outlet 162 for the chopped or cut fibers.

After the roving is cut, the cut fibers are expelled from the cutter 20(see FIG. 1) into the resin sprays of the spray gun 22 in such a manneras to assure good wetting of fibers with resin. Ideally, the spraypattern of the spray gun and the pattern of the cut fibers leaving thecutter should match. To assist in matching the pattern of the cut fibersdischarged from the cutter to that of the spray gun, the cutter isprovided with pattern adjusting means comprising air jet means directedinto the cut fibers being discharged from the cutter. Preferably, theair supplied for this purpose is separate from that supplied to the airmotor 44 so that adjustment of the pattern of the cut fibers will notalter the speed of rotation of the cutter roller and the amount of fiberbeing cut, or vice versa. As is shown in FIGS. 4 and 10, the air inletpassage 72 is intersected by a second air passage 170 which is not underthe influence of the speed control valve 74. The flow through thepassage 170 is controlled by a separate air valve 172 of the needlevalve type, having a stem extending threading through the body 51 formanual adjustment from the exterior thereof independently of the valve74. From the air valve 172, the air flows through a passage 174 formedin the central body 51 to a pattern control tube 178 located in anopening 176 in the mounting plate 42 and contained within the cover 159.The inner end of the tube 178 extends into the opening 176 andcommunicates with the passage 174. The central portion of the tube 178has three openings therein, the center opening 181 being about 1/16th ofan inch in diameter and the other openings 182 being about 3/64ths of aninch in diameter. The center opening 181 is located approximately on thecentral vertical plane of the rollers 86, 126 and 127, while theadjacent openings 182 are about 3/16ths of an inch from the opening 181.The openings 181 and 182 are preferably directed at an angle of about45° toward the outlet 162 and are held in this position by a set screw184 threadedly engaged in the mounting plate 42. The outer end of thetube 178 is plugged by a removable screw 186, which together with theset screw 184 facilitates removal and cleaning of the tube 178 shouldthat become necessary.

To maintain internal cleanliness, some of the exhaust air from the motor44 is vented through the passage 82 in the plate 42 to keep the rollersclean and in particular to blow loose fibers or fuzz off the blades 116as they move into cutting position.

The operation of the cutter 20 of the present invention will now bedescribed in conjunction with the spray gun 22. Assume that the cutterhas been installed on the spray gun 22, roving 169 has been threadedthrough the cutter 20, and sharp blades 116 have been installed, aspreviously described. The operator holds the assembled cutter 20 andspray gun 22 by the spray gun handle with one hand and has his otherhand free. The operator squeezes the trigger 34 of the gun, and resinsprays 171 and 172 and cut roving 173 are discharged from the gun andcutter. If necessary, the operator loosens screws 38 and 40 to properlyadjust the cutter relative to the gun and then tightens the screws. Theoperator then adjusts the air motor speed control valve 74 so that therate of discharge of roving is matched to the rate of discharge of resinfrom the gun. If necessary, the operator adjusts the clearance betweenthe cutter roller 86 and friction roller 126 and between the frictionroller 126 and idler roller 127 while the cutter 20 is operated byturning the adjustment screw 144 and locking it in the desired position.Finally, the operator adjusts the air jets controlling the pattern ofthe cut roving by turning the valve 172 so that the pattern of theexpelled cut fibers matches that of the resin spray gun. All theseoperations are easily carried out by the operator since he has one freehand and all the adjustments are easily accessible. After satisfactoryadjustments are made, the cutter 20 and spray gun 22 can be directedonto the work. Should it become necessary, periodic changes oradjustments can be made in motor speed, roller contact, blade cuttingpressure, and the pattern of the cut roving without having to ceaseoperation.

While only one embodiment of the present invention has been fullydescribed and illustrated, it should be understood that variations,modifications and rearrangements may be made therein without departingfrom the scope of the invention as defined by the appended claims.

We claim:
 1. In a roving cutter having a rotatable cutter roller, arotatable back-up roller cooperating with said cutter roller, and anidler roller cooperating with said back-up roller for feeding rovingbetween said cutter roller and said back-up roller, the improvementcomprising means adjustably mounting said back-up roller for movementinto engagement with both of said cutter and idler rollers and insubstantially equal increments away from both of them, and positivedisplacement adjusting means connected with said mounting means forfixing the position of said back-up roller relative to said cutter andidler rollers, said adjusting means including manually operable meansremote from said rollers for adjusting said back-up roller while thecutter is operating, whereby the clearance between said idler andback-up rollers remains substantially equal to and varies substantiallyequally with the clearance between said cutter and back-up rollers. 2.In a roving cutter having a rotatable cutter roller, a rotatable back-uproller cooperating with said cutter roller, and an idler rollercooperating with said back-up roller for feeding roving between saidcutter roller and said back-up roller, the improvement comprising meansadjustably mounting said back-up roller for movement toward and awayfrom both of said cutter and idler rollers in substantially equalincrements relative to each of them, and positive displacement adjustingmeans connected with said mounting means for fixing the position of saidback-up roller relative to said cutter and idler rollers, whereby theclearance between said idler and back-up rollers remains substantiallyequal to and varies substantially equally with the clearance betweensaid cutter and back-up rollers.
 3. In a roving cutter as set forth inclaim 2, said adjusting means including manually operable means remotefrom said rollers for adjusting said back-up roller while the cutter isoperating.
 4. In a roving cutter having a rotatable cutter roller, arotatable back-up roller cooperating with said cutter roller, and anidler roller cooperating with said back-up roller, the improvementcomprising means adjustably mounting said back-up roller for movementinto engagement with both of said cutter and idler rollers and insubstantially equal increments away from both of them, and positivedisplacement adjusting means connected with said mounting means forfixing the position of said back-up roller relative to said cutter andidler rollers, said adjusting means including manually operable meansextending upwardly from the cutter remote from said rollers foradjusting said back-up roller while the cutter is operating, whereby theclearance between said idler and back-up rollers remains substantiallyequal to and varies substantially equally with the clearance betweensaid cutter and back-up rollers.
 5. In a roving cutter for attachment toa hand-held resin spray gun having an operator grippable handleextending downwardly in the normal operation of the gun, the rovingcutter having a cutter roller, a rotatable back-up roller cooperatingwith said cutter roller, and an idler roller cooperating with saidback-up roller, the improvement comprising means adjustably mountingsaid back-up roller for movement into engagement with both of saidcutter and idler rollers and in substantially equal increments away fromboth of them, and positive displacement adjusting means connected withsaid mounting means for fixing the position of said back-up rollerrelative to said cutter and idler rollers, said adjusting meansincluding manually operable means extending outwardly to a freelyaccessible location remote from said rollers when said spray gun is inits normal operating position for adjusting said back-up roller whilethe cutter is operating, whereby the clearance between said idler andback-up rollers remains substantially equal to and varies substantiallyequally with the clearance between said cutter and back-up rollers. 6.In a roving cutter for attachment to a hand-held resin spray gun havingan operator grippable handle extending downwardly in the normaloperation of the gun, the roving cutter having a rotatable cutterroller, a rotatable back-up roller cooperating with said cutter roller,and an idler roller cooperating with said back-up roller for feedingroving between said cutter and back-up rollers, the improvementcomprising means adjustably mounting said back-up roller for movementinto engagement with both of said cutter and idler rollers and insubstantially equal increments away from both of them, and positivedisplacement adjusting means connected with said mounting means forfixing the position of said back-up roller relative to said idler andcutter rollers, said adjusting means including manually operable meansextending outwardly to a freely accessible location remote from saidrollers when said spray gun is in its normal operating position foradjusting said back-up roller while the cutter is operating, whereby theclearance between said idler and back-up rollers remains substantiallyequal to and varies substantially equal with the clearance between saidcutter and back-up rollers.